Initial steps on db layer rework - planning and prototyping

pkg/runtime/db/driver.go

@@ -0,0 +1,48 @@
+package db
+
+import (
+	"fmt"
+	"sync"
+)
+
+type Driver interface {
+	GetName() string
+	Open(dataSourceName string) (Store, error)
+	Close() error
+}
+
+var (
+	driversMu sync.RWMutex
+	drivers   = make(map[string]Driver)
+)
+
+func RegisterDriver(driver Driver) {
+	driversMu.Lock()
+	defer driversMu.Unlock()
+
+	if driver == nil {
+		panic("db: can't register nil driver")
+	}
+
+	name := driver.GetName()
+	if len(name) == 0 {
+		panic(fmt.Sprintf("db: can't register driver with empty name: %T", driver))
+	}
+
+	if _, duplicated := drivers[name]; duplicated {
+		panic("db: register called twice for driver: " + name)
+	}
+
+	drivers[name] = driver
+}
+
+func Open(name string, dataSourceName string) (Store, error) {
+	driversMu.RLock()
+	defer driversMu.RUnlock()
+
+	if driver, exists := drivers[name]; exists {
+		return driver.Open(dataSourceName)
+	} else {
+		return nil, fmt.Errorf("can't find driver: %s", name)
+	}
+}

pkg/runtime/db/index.go

@@ -0,0 +1,4 @@
+package db
+
+// list of participating values for specific index
+type Index func(name string, value Storable) ([]interface{}, error)

pkg/runtime/db/store.go

@@ -0,0 +1,17 @@
+package db
+
+type Store interface {
+	Get(result Storable, key string) error
+	List(result []Storable, query ...*Query) error
+
+	// using key if provided or getting key from obj
+	Delete(obj Storable, key string) error
+
+	// do we need DeleteMatching(dataType Storable, query *Query) error
+	// hm, choose needed from Insert, Update, UpdateMatching, Upsert
+
+	Update(obj Storable, inPlace bool) error
+}
+
+type Query struct {
+}

pkg/runtime/db/todo.txt

@@ -0,0 +1,12 @@
+// todo separate index types and implement only needed
+//	 	like
+//      * first / last with field value (for getting last version or first / last revision for specific status or policy version)
+//      * list with field value (for getting all revisions for specific policy)
+// current name -> reference
+// no namespace in default object, only in policy objects
+// ... -> key (ns/name or ns or "system" for revision/policy/etc.)
+// use binary.LittleEndian.PutUint64 to form bolt keys (optimization)
+// no need for Deleted interface, just have this field in policy objects and change it with saving it by in place update
+// create automatic index that stores last version of the versioned object aka type=last
+// get should use index to get last version (if versioned)
+// finding & setting new generation should be in the same tx with actual update

pkg/runtime/db/types.go

@@ -0,0 +1,76 @@
+package db
+
+import (
+	"fmt"
+	"sync"
+)
+
+type Kind = string
+type Key = string
+
+type Storable interface {
+	GetKind() Kind
+	GetKey() Key
+}
+
+type Versioned interface {
+	Storable
+	GetVersion()
+	SetVersion()
+}
+
+type TypeInfo interface {
+	Kind() Kind
+	Indexes() map[string]Index
+	IsVersioned() bool
+	//New() Storable
+	//NewSlice() []Storable
+}
+
+var (
+	typeInfosMu sync.RWMutex
+	typeInfos   = make(map[Kind]TypeInfo)
+)
+
+func RegisterType(storable Storable, indexes ...*Index) {
+	typeInfosMu.Lock()
+	defer typeInfosMu.Unlock()
+
+	if storable == nil {
+		panic("db: can't register nil type")
+	}
+
+	kind := storable.GetKind()
+	if len(kind) == 0 {
+		panic(fmt.Sprintf("db: can't register type with empty kind: %T", storable))
+	}
+
+	if _, duplicated := typeInfos[kind]; duplicated {
+		panic(fmt.Sprintf("db: register called twice for type: %T", storable))
+	}
+
+	typeInfos[kind] = buildTypeInfo(storable, indexes)
+}
+
+func buildTypeInfo(storable Storable, indexes []*Index) TypeInfo {
+	// todo verify object, indexes and fill in the type info object
+	return &reflectTypeInfo{}
+}
+
+type reflectTypeInfo struct {
+	kind        Kind
+	indexes     map[string]Index
+	isVersioned bool
+}
+
+func (info *reflectTypeInfo) Kind() Kind {
+	return info.kind
+}
+
+func (info *reflectTypeInfo) Indexes() map[string]Index {
+	return info.indexes
+}
+
+func (info *reflectTypeInfo) IsVersioned() bool {
+	return info.isVersioned
+}